Electric arc breaker



. April 26, 1938. K. U'rsUNoMlYA ELECTRIC ARC BREAKER Filed Aug. 19,1935 EES INVENTOR. Enzo UrsuNoM/yn 71j.. ATTOR EYS.

Patented Apr. 26, 193s` UNITED STATES PATENT OFFICE ELECTRIC ARC BREAKERKenzo Utsunomiya, Shiba-ku, Tokyo, Japan Application August 19, 1935,Serial No. 36,785

1 Claim. (Cl. 200-131) The present invention relates to an electric fusedevice, which consists in providing an elastic thin walled cylinderencircling a fusible member and v mounted in an outer insulatingcylinder, whereby 5 the breaking of the arc formed by the fusing of thefusible member is accelerated by utilizing the interna] pressureproduced upon the formation of an arc to .discharge the fusible memberfrom the outer cylinder. The fusible member is suitably enclosed toprevent dust and moisture from entering the interior of the device so asto make it suitable for use for a high voltage circuit and increase thelife of the device. The object of the invention is to control thescattering of the electric are and burnt metal powder produced when thefusible member is fused, and also to prevent the burning and destructionof the outer insulating cylinder.

The appended drawing shows as an example three embodiments of theelectric fuse device according to this invention, wherein Figure 1 is alongitudinal elevation of the rst embodiment of the electric fuse deviceaccording to this invention;

Figure 2 is a view looking at the bottom of Fig. 1:

Figure 3 is a side view of the second embodiment, partly broken away;and

Figure 4, a side view of a high voltage electric fuse device which isthe third embodiment, partly broken away.

'I'he embodiment of the invention illustrated in Figs. 1 and 2 of theaccompanying drawing, comprises an outer insulating cylinder Imade ofglass or other transparent insulating material having electricconducting terminal pieces 2 and 3 of tubular form fixed to both ends ofthe outer insulating cylinder by a binding material 4 or other suitablemeans. A fusible member Sis mounted sub- 40 stantially centrally in theouter insulating cylinder I by a plate 6 of electric conducting materialconnected to an end portion of the fusible member and engaged in theterminal piece 2 to fix said end portion of the fusible member inposition on the interior of the terminal piece 2 with a nut 1 screwthreaded in the piece 2 to retain the plate in position. The terminalpiece 2 is closed tigl' .ly by the plate 6, nut 1 and a cap 8 which isprovided vwhen necessary. A cap 9 is inserted in the open end of theterminal piece 3 and secured therein Around the fusible member 5 thereis arranged one or more inner insulating cylinders H, II which are madeby rolling or pasting together a resilient or elastic insulatingmaterial such as cellophane, uninflammablc Celluloid, or the 5 like,into cylindrical shape. To the plate 6 and cap 9 there are attachedshort metallic tubes I2 respectively, and in the interior or exterior ofwhich there is engaged the inner insulating cylinder II to support thesaid cylinder' II' and 10 also receive pressure as describedhereinafter.

, The inner insulating cylinder II is wound spirally with an electricconducting sheetI I3 such as a tin foil, or the like, and is connectedto an electric conducting ring I4 by a conducting wire, so 15 that itmay not only be expelled with'the cap 9 from the cylinder I, but alsothc tin foil I3 may be of the same potential as the terminal piece 3,thus preventing the formation of corona. The elastic legs I0 are fixedto the cap 9 as'shown in Fig. 20 2 and to maintain the legs inengagement with the periphery of the terminal piece 3 there is provideda clamping ring I5, for example, a locking wire or tightening plate.Further, by inserting the periphery of the cap 9 in the peripheral 2.-groove I1 of the terminal piece 3 and packing this part with a sealingagent such as litharge or gum packing the electric fuse device may begiven a watertight construction suitable for th outdoor use. 30

The following is an explanation of the operation of the electric fusedevice of the present invention.

When the fusible member 5 starts fusing at a starting point which is areduced portion I6, inf- 35 ternal pressure is produced in the innerinsulating cylinder I I by the fusing of said fusible member. 'I'hispressure is received by the short metallic tube I2 due to the elasticityof the cylinder II'. above internal pressure directly to the cap 9without allowing it to escape out of the inner insulating tube I I. Thiscauses the cap 9 metallic tube I2, the remaining part of the fusiblemember 5 and the insulating tube II to be expelled to- 45 gether as aunit from the terminal piece 3, releasing the connection between theterminal piece 3 and resilient legs I0.

As in this invention there is provided the metallic tube I2 adapted forboth supporting the 50 inner insulated cylinder II' and receivingpressure as described hereinbefore, it is possible to obtain suchconstruction that the inner cylinder II' is easily supportedconcentrically with the fusible member 5 and the internal pressure iro-55 That is to say, said tube I2 transmits the 40 duced in the innercylinder II is made to act upon the cap ilv effectively. Thus, even incase of low or high voltage the expulsion due to the internal pressureis effected satisfactorily, so that the blowing of the fusible member isdone quickly and accurately, especially when the device is used inconnection with an electric current of a high voltage.

In the embodiments of the invention shown in Figs. 3 and 4, there isprovided a transparent outer insulating cylinder I8 in which there isinserted one or more inner insulating cylinders 20 and 20 formedtubularly of a thin sheet such as a regenerated cellulose sheet(popularly known as cellophane), a fibreV coated with regeneratedcellulose or a starchy sheet, for example, oblate. The inner insulatingcylinder 20 is expanded by the internal pressure produced upon theformation of an arc in an arcing circuit provided in the inner cylinderand is shrunk axially by the high vacuum induced with the escape of theinternal pressure, thereby pressing and dispersing the arc and thusincreasing the current density of the unit arc and extinguishing it. Toboth ends of the outer insulating cylinder I8 there is engaged ametallic cap 22 which is united tightly to the outer cylinder I8 by asuitable binding agent, as indicated at 23. The said cap has va screwthread at its outer end portion and also has a central opening in saidend. Also, there is screwed to the cap 22 a cap-shaped piece 24 whichhas an air outlet `25. A fusible member 2 I is mounted in the innercylinder 20 in such a manner so that the fusible member does not contactwith the cylinder. Both ends of this fusible member are bent to a YorT-shape and the end portions of such Y-shaped portions are benthorizontally. Then, the bent horizontal end portions thus formed areinserted between the outer end of the cap 22 and cap-shaped piece 24. Ifthe fusible member 2| or arcing circuit is disposed on the axial line ofthe insulating cylinder I8 and. is fused or broken, the temperature willbev raised'quickly owing to the formation of an arc 20 in an instant andpresses the air or liquid bethe opening 25 immediately high vacuum isinduced in the inner cylinder 20 by its reaction to shrink the cylinder20 axially and rapidly as if it were to collapse the arc by tightening,and as the high temperature is lowered by having part of it absorbed bythe inner wall of the inner cylinder, the effect of so-called surfacedeionization ls great. Thus, by applying pressure reactionally at thesame time with the formation of an arc and absorbing its h eat energythe arc is quenched.

The burnt metallic powder produced upon the formation of an arc adheresto the inner Wall of the inner insulating cylinder, and not to the outercylinder. Therefore, there is no apprehension of the insulation beingreduced by the attachment of the metallic powder, and even when cuttingoff a high voltage current, the object of protecting the outerinsulating cylinder by the above action is readily attained. Moreover,with a closed type of electric fuse device the desired action is foundto be successful owing to the high vacuum created in the cylinder (atthe time of fusing) without burning ven an inflammable object. If theinner cylinder 20 has a diameter the same or larger than the diameter ofthe air outlet 25 and is long enough to contact internally with theopening 25 or to reach the edge of the inner end of the cap 2 2, it canbe expanded without interference by the internal pressure produced uponthe formation of an arc shown`engaged in an enlarged intermediateportion of the outer insulating cylinder I8 to doubly protect said outercylinder during the fusing of the fusible member.

Iclaim:

An electric fuse member comprising an outer cylinder of insulatingmaterial, tubular terminals of conducting material mounted on oppositeends of the cylinder, a fusible member disposed in said cylinder andelectrically connected at its opposite ends with said terminal members,a flexible cylinder of insulating material disposed Within the outercylinder and encircling said fusible member, said flexible cylinderbeing subject to expansion under pressure developed therein by theformation of an arc, and end-closing members carried by said terminalsand adapted to permit escape of such pressure to cause the flexiblecylinder to contract and thereby create a partial vacuum therein.

KENZO UTSUNOMIYA.

